The trachea divides into two main stem bronchi at the level of which anatomical landmark?

• A. Epiglottis
• B. Alveoli
• C. Carina
• D. Larynx

Answer: (C)

The split of the trachea into the right and left main bronchi occurs at a ridge called the carina. This landmark sits at the lower end of the trachea, roughly at the level of the sternal angle (angle of Louis), around the fourth to fifth thoracic vertebra. The carina marks the bifurcation point and is a sensitive area that can trigger coughing if irritated. The other structures aren’t where the trachea divides: the epiglottis is at the top of the airway, guarding the entrance to the larynx; the larynx itself is above the trachea; and the alveoli are the tiny air sacs at the ends of the bronchioles, far distal from the bifurcation.